| 1 | SLR | Sobelair | IATA: Q7, Callsign: Sobelair, Ceased operations | B | AVCODES |
| 2 | SLR | Silverjet plc | IATA: Y7, Callsign: Silverjet, IATA Prefix: 362, Ceased operations on 30 May 2008. | GB | AVCODES |
| 3 | SLR | Silverstone Air Services Ltd | IATA: K5, Callsign: Silverstone, | EAK | AVCODES |
| 4 | SLR | Los Angeles and Salt Lake R.R. Co. (Salt Lake Route) | 8/1920 | | NAKINA |
| 5 | SLR | Los Angeles and Salt Lake R.R. Co. (Union Pacific System) | 7/1923-7/1935 | | NAKINA |
| 6 | SLR | San Pedro, Los Angeles & Salt Lake R.R. (Los Angeles and Salt Lake R.R. Co.) | 8/1920 | | NAKINA |
| 7 | SLR | St. Lawrence & Atlantic R.R. Co. | added 10/1989; 1/1994-7/2005 | | NAKINA |
| 8 | SLR | St. Lawrence & Atlantic R.R. Co. | added 10/89; 1/94-7/2000 | | NRHS |
| 9 | SLR | *SAN PEDRO, LOS ANGELES & SALT LAKE RAILROAD [LOS ANGELES & SALT LAKE RAILROAD CO.} | | | PWRC |
| 10 | SLR | +ST. LAWRENCE & ATLANTIC RAILROAD COMPANY | | | PWRC |
| 11 | SLR | St. Lawrence and Atlantic Railroad (Genesee & Wyoming) | | | RSRV |
| 12 | SLR | St. Lawrence & Atlantic | | CDN | TRAFFIC |
| 13 | SLRA | SALAS RAMIREZ, LETICIA | | | SCAC4 |
| 14 | SLRD | Sri Lanka Railway Department | | CL | TRAFFIC |
| 15 | SLRE | SALINAS ALANIS, RENE | | | SCAC4 |
| 16 | SLRF | SHOWA LINE, LTD | | | PWRC |
| 17 | SLRG | San Luis & Rio Grande R.R. Inc. | added 10/2003; 7/2005; eliminated 4/2007 | | NAKINA |
| 18 | SLRG | SAN LUIS & RIO GRANDE RAILROAD INC. | | | PWRC |
| 19 | SLRG | San Luis and Rio Grande Railroad | | | RSRV |
| 20 | SLRG | SAN LUIS & RIO GRANDE RAILROAD INC | | | SCAC4 |
| 21 | SLRG | San Luis & Rio Grande R.R. Inc. | | USA | TRAFFIC |
| 22 | SLRJ | SLEIGHT, ROBERT J | | | SCAC4 |
| 23 | SLRL | SHELL, RUSSELL L | | | SCAC4 |
| 24 | SLRM | SCORPIO LR TWO (2) POOL LTD | | | SCAC4 |
| 25 | SLRR | St. Lawrence & Raquette River R.R. | added 7/1990; eliminated 1/1994; 1/1994 (not listed) | | NAKINA |
| 26 | SLRR | St. Lawrence & Raquette River R.R. | added 7/90; eliminated 1/94 | | NRHS |
| 27 | SLRR | ST. LAWRENCE & RAQUETTE RIVER RAILROAD | | | PWRC |
| 28 | SLRR | STEWART-LINER TRANSPORTATION CORP | | | SCAC4 |
| 29 | SLRS | SMS Rail Service, Inc. | 7/2000-7/2005 | | NAKINA |
| 30 | SLRS | SMS Rail Service, Inc. | Jul-00 | | NRHS |
| 31 | SLRS | SMS RAIL SERVICE, INC. | | | PWRC |
| 32 | SLRS | SMS Rail Service | | | RSRV |
| 33 | SLRS | SMS RAIL SERVICE INC | | | SCAC4 |
| 34 | SLRS | SMS Rail Service, Inc. | | USA | TRAFFIC |
| 35 | SLRU | SILVA LS SP. Z O.O. | | PL | BIC |
| 36 | SLRU | SHOWA LINE, LTD. | | | PWRC |
| 37 | SLRU | Showa Line Limited | | | RSRV |
| 38 | SLRU | SWAN CONTAINER LINE GMBH & CO KG | | | SCAC4 |
| 39 | SLRW | SKYLINE RAILINGS & WINDOWS INC | | | SCAC4 |
| 40 | SLRX | St. Louis Refrigerator Car Co. (Manufacturers' Ry. Co.) | 8/1920-7/1923 | | NAKINA |
| 41 | SLRX | St. Louis Refrigerator Car Co. | 7/1935-4/1970; eliminated 4/1973; added 1/1974; 1/1975; eliminated 1/1975; added 10/1975; 1/1980; eliminated 4/1981 | | NAKINA |
| 42 | SLRX | St. Louis Refrigerator Car Co. | 4/38-4/70; eliminated 4/73; added 1/74; 1/75; eliminated 1/75; 1/80; eliminated 4/81 | | NRHS |
| 43 | SLRX | *MANUFACTURERS' RWY. CO. [ST. LOUIS REFRIGERATOR CAR CO.] | | | PWRC |
| 44 | SLRX | *SWEET LINE RAILROADSLS SEA-LAND SERVICE, INC. | | | PWRC |
| 45 | SLRX | St. Louis Refrigerator Car | | | RSRV |
